Magnetic tunnel effect type magnetic head, and recorder/player

ABSTRACT

In a magnetic tunnel effect type magnetic head  20  having a magnetic tunnel junction element  26  sandwiched with conductive gap layers  25  and  27  between a pair of magnetic shielding layers  24  and  28 , the conductive gap layers  25  and  27  are formed from at least one nonmagnetic metal layer containing a metal element selected from Ta, Ti, Cr, W, Mo, V, Nb and Zr. Therefore, the magnetic head  20  can have an improved face opposite to a magnetic recording medium.

RELATED APPLICATION DATA

The present application is a continuation of U.S. application Ser. No.09/897,236 filed Jul. 2, 2001, now U.S. Pat. No. 6,909,584 which claimspriority to Japanese Application No. P2000-205926 filed Jul. 6, 2000,all of which are incorporated herein by reference to the extentpermitted by law.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic tunnel effect type magnetichead having a magnetic tunnel junction element sandwiched withconductive gap layers between a pair of magnetic shielding layers, and arecorder/player adapted to record and/or play back a signal to and/orfrom a magnetic recording medium by the use of the magnetic tunneleffect type magnetic head.

2. Description of the Related Art

It is well known as a so-called magnetic tunnel effect that in alaminated structure having a thin insulative layer sandwiched between apair of magnetic layers, when a predetermined voltage is applied betweenthe pair of magnetic layers, the conductance of a so-called tunnelcurrent varies depending upon the relative angle of magnetizationbetween the pair of magnetic layers. That is, the laminated structurehaving the thin insulative layer sandwiched between the pair of magneticlayers shows a magneto-resistive effect to the tunnel current flowingthrough the insulative layer.

With the magnetic tunnel effect, it is possible to theoreticallycalculate the magneto-resistive coefficient or ratio between the pair ofmagnetic layers owing to the polarizability of the magnetic layers whenmagnetized, and more specifically, to have a magneto-resistivecoefficient or ratio of about 40% in case the pair of magnetic layers isformed from Fe.

Thus, as a magneto-resistive effect element, the magnetic tunneljunction element (will be referred to as “TMR element” hereunder) havinga laminated structure having a thin insulative layer sandwiched betweena pair of magnetic layers has been attracting the attention in the fieldof this art. Especially in the field of magnetic heads, attention isfocused on a so-called magnetic tunnel effect type magnetic head (willbe referred to as “TMR head” hereunder) using the TMR element as amagneto-sensitive element to detect a magnetic signal from a magneticrecording medium.

Referring now to FIG. 1, there is schematically illustrated such aconventional TMR head by way of example. FIG. 1 is a schematic end viewof the TMR head from a recording medium side. The TMR head is generallyindicated with a reference 100.

As shown in FIG. 1, the TMR head 100 is a so-called shielded TMR headhaving a TMR element 104 sandwiched with a gap layer 103 between a pairof upper and lower magnetic shielding layers 101 and 102. The TMR head100 is of a laminated structure in which the above component elementsare formed on a substrate 105 by the thin-film laminating process. Inthe TMR head 100, the pair of magnetic shielding layers 101 and 102functions as electrodes for the TMR element 104. There are sandwichedbetween the pair magnetic shielding layers 101 and 102 nonmagneticconductive layers 106 and 107 of the gap layer 103 which electricallyconnect the pair of shielding layers 101 and 102 and the TMR element 104to each other. Also, in the TMR head 100, a part of the TMR element 104,abutting a projection 107 a of the nonmagnetic conductive layer 107,serves as a magnetic sensor portion 104 a of the TMR element 104. Themagnetic sensor portion 104 a has a reading track width of Tw.

Referring now to FIG. 2, there is schematically illustrated aconventional shielded MR (magneto-resistive) head by way of example.FIG. 2 is a schematic end view of the MR head from a recording mediumside. The MR head is generally indicated with a reference 200. As shownin FIG. 2, the MR head 200 has an MR element 204 and a pair of upper andlower conductive layers 205 and 206 formed at either end of the MRelement 204, sandwiched with a gap layer 203 between a pair of upper andlower magnetic shielding layers 201 and 202. The MR head 200 is of alaminated structure in which the above component elements are formed ona substrate 207 by the thin-film forming process. In the MR head 200, apart of the MR element 204, laid between the pair of conductive layers205 and 206, serves as a magnetic sensor portion 204 a of the MR element204. The magnetic sensor 204 a has a reading track width of Tw.

In the shielded MR head 200, as the gap is decreased for a higherrecording density, the nonmagnetic nonconductive layer which forms thegap layer 203 is thinner. More specifically, because of steps formed bythe pair of conductive layers 205 and 206 disposed on the opposite endsof the MR element, it is difficult to form the upper nonmagneticnonconductive layer to a uniform thickness over the MR element 204. Incase the distance between the pair of magnetic shielding layers 201 and202 and the MR element 204, that is, the inter-shield distance, isdecreased for reading a signal recorded with a high density in amagnetic recording medium, it is extremely difficult to secure aninsulation between the pair of magnetic shielding layers 201 and 202 andthe MR element 204.

On the contrary, in the TMR head 100 shown in FIG. 1, the pair ofmagnetic shielding layers 101 and 102 function as electrodes so that thegap layer 103 can be made thin and thus the distance between the pair ofmagnetic shielding layers 101 and 102 and the TMR element 104 can bedecreased. Therefore, in the TMR head 100, the gap can be made narrow toenable a high density of recording to a magnetic recording medium.

For production of the above-mentioned TMR head 100, a generallydisc-like substrate is prepared, the component elements of the TMR head100 are formed one on the other on the substrate by the thin-filmforming process, and then the substrate is cut into individual headchips, thereby producing a plurality of TMR heads 100 collectively.

However, in the process of producing the TMR head 100, the nonmagneticconductive layers 106 and 107 forming together the gap layer 103 areelongated without being polished, when the height of the TMR element 104in the direction of its depth is adjusted by polishing it on a surfaceplate, so that the pair of magnetic shielding layers 101 and 102sandwiching the TMR element 104 between them will electrically beshort-circuited between them as the case may be. That is, a defect 108is caused in the medium-opposite face of the produced TMR head 100 bythe elongation of the nonmagnetic conductive layers 106 and 107 in somecases as shown in FIG. 3.

In this TMR head 100 thus produced, no current will flow through themagnetic sensor portion 104 a of the TMR element 104 and little playbackoutput will be detected from the magnetic recording medium.

OBJECT AND SUMMARY OF THE INVENTION

It is therefore an object of the present invention to overcome theabove-mentioned drawbacks of the prior art by providing animproved-yield, high-quality magnetic head of a magnetic tunnel effecttype having a structure in which a magnetic tunnel junction element issandwiched with conductive gap layers between a pair of magneticshielding layers and thus having an improved face opposite to a magneticrecording medium, and a recorder/player which records and/or plays backa signal to and/or from a magnetic recording medium by the use of suchan MR head.

The above object can be attained by providing a magnetic tunnel effecttype magnetic head having a magnetic tunnel junction element sandwichedwith conductive gap layers between a pair of magnetic shielding layers.The conductive gap layer is formed from at least one nonmagnetic metallayer containing a metal element selected from Ta, Ti, Cr, W, Mo, V, Nband Zr.

Since the conductive gap layer in the above magnetic tunnel effect typemagnetic head is formed from at least one nonmagnetic metal layercontaining a metal element selected from Ta, Ti, Cr, W, Mo, V, Nb andZr, the magnetic head can have an improved face opposite to a magneticrecording medium.

Also, the above object can be attained by providing a magnetic tunneleffect type magnetic head having a magnetic tunnel junction elementsandwiched with conductive gap layers between a pair of magneticshielding layers. The conductive gap layer is formed from at least onenonmagnetic metal layer containing an alloy of two or more elementsselected from Al, Pt, Cu, Au, Ta, Ti, Cr, W, Mo, V, Nb and Zr.

Since the conductive gap layer in the above magnetic tunnel effect typemagnetic head is formed from at least one nonmagnetic metal layercontaining an alloy of two or more elements selected from Al, Pt, Cu,Au, Ta, Ti, Cr, W, Mo, V, Nb and Zr, the magnetic head can have animproved face opposite to a magnetic recording medium.

Also, the above object can be attained by providing a recorder/playerwhich records and/or plays back a signal to and/or from a magneticrecording medium by the use of a magnetic tunnel effect type magnetichead having a magnetic tunnel junction element sandwiched withconductive gap layers between a pair of magnetic shielding layers. Theconductive gap layer in the magnetic tunnel effect type magnetic head isformed from at least one nonmagnetic metal layer containing a metalelement selected from Ta, Ti, Cr, W, Mo, V, Nb and Zr. Therefore, therecorder/player can record and/or play back a signal to and/or from themagnetic recording medium.

Since the conductive gap layer in the magnetic tunnel effect typemagnetic head used in the above recorder/player is formed from at leastone nonmagnetic metal layer containing a metal element selected from Ta,Ti, Cr, W, Mo, V, Nb and Zr, the magnetic head can have an improved faceopposite to a magnetic recording medium.

Also, the above object can be attained by providing a recorder/playerwhich records and/or plays back a signal to and/or from a magneticrecording medium by the use of magnetic tunnel effect type magnetic headhaving a magnetic tunnel junction element sandwiched with conductive gaplayers between a pair of magnetic shielding layers. The conductive gaplayer in the magnetic tunnel effect type magnetic head is formed from atleast one nonmagnetic metal layer containing an alloy of two or moreelements selected from Al, Pt, Cu, Au, Ta, Ti, Cr, W, Mo, V, Nb and Zr.

Since the conductive gap layer in the magnetic tunnel effect typemagnetic head used in the above recorder/player is formed from at leastone nonmagnetic metal layer containing an alloy of two or more elementsselected from Al, Pt, Cu, Au, Ta, Ti, Cr, W, Mo, V, Nb and Zr, themagnetic head can have an improved face opposite to a magnetic recordingmedium. Therefore, the recorder/player can record and/or play back asignal to and/or from the magnetic recording medium.

These objects and other objects, features and advantages of the presentintention will become more apparent from the following detaileddescription of the preferred embodiments of the present invention whentaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an end view of the essential portion of the conventionalshielded TMR head from the face thereof opposite to a recording medium,taken for explanation of the construction of the TMR head;

FIG. 2 is an end view of the essential portion of the conventionalshielded TMR head from the face thereof opposite to a recording medium,taken for explanation of the construction of the TMR head;

FIG. 3 is an end view showing the shielded TMR head in which a defecthas taken place;

FIG. 4 is a schematic perspective view of an example of hard disc drive;

FIG. 5 is a schematic perspective view of a head slider of the hard discdrive shown in FIG. 4;

FIG. 6 is an end view of the essential portion of the magnetic headaccording to the present invention, from the face thereof opposite to arecording medium;

FIG. 7 is a schematic plan view of a first soft magnetic layer formed ona substrate in the process of head slider production;

FIG. 8 is a schematic sectional view taken along the line X₁-X₁′ in FIG.7

FIG. 9 is a schematic plan view of a first resist pattern formed on thefirst soft magnetic layer in the process of head slider production;

FIG. 10 is a schematic sectional view taken along the line X₂-X₂′ inFIG. 9

FIG. 11 is a schematic plan view of a lower shielding layer formed onthe substrate in the process of head slider production;

FIG. 12 is a schematic sectional view taken along the line X₃-X₃′ inFIG. 11;

FIG. 13 is a schematic plan view of a first nonmagnetic nonconductivelayer formed on the substrate and polished until the surface of thelower shielding layer is exposed, in the process of head sliderproduction;

FIG. 14 is a schematic sectional view taken along the line X₄-X₄′ inFIG. 13;

FIG. 15 is a schematic plan view of a first nonmagnetic conductive layerformed on the flattened substrate in the process of head sliderproduction;

FIG. 16 is a schematic sectional view taken along the line X₅-X₅′ inFIG. 15;

FIG. 17 is a schematic plan view of a magnetic tunnel junction layerformed on the first nonmagnetic conductive layer in the process of headslider production;

FIG. 18 is a schematic sectional view taken along the line X₆-X₆′ inFIG. 17;

FIG. 19 is a schematic plan view of a second resist pattern formed onthe magnetic tunnel junction layer in the process of head sliderproduction;

FIG. 20 is a schematic sectional view taken along the line X₇-X₇′ inFIG. 19;

FIG. 21 is a schematic plan view of a lower nonmagnetic conductive layerand magnetic tunnel junction layer formed on the lower shielding layerin the process of head slider production;

FIG. 22 is a schematic sectional view taken along the line X₈-X₈′ inFIG. 21;

FIG. 23 is a schematic plan view of a second nonmagnetic conductivelayer and magnetic tunnel junction layer formed on the substrate andpolished until the surface of the magnetic tunnel junction layer isexposed, in the process of head slider production

FIG. 24 is a schematic sectional view taken along the line X₉-X₉′ inFIG. 23;

FIG. 25 is a schematic plan view of a recess formed around a portion ofthe magnetic tunnel junction layer which is to be a magnetic sensor ofthe TMR element in the process of head slider production;

FIG. 26 is a schematic sectional view taken along the line X₁₀-X₁₀′ inFIG. 25;

FIG. 27 is a schematic plan view of a third resist pattern formed rightabove the magnetic sensor of the TMR element in the process of headslider production;

FIG. 28 is a schematic sectional view taken along the line X₁₁-X₁₁′ inFIG. 27;

FIG. 29 is a schematic plan view of a third nonmagnetic nonconductivelayer having a contact hole, formed right above the magnetic sensor ofthe TMR element in the process of head slider production;

FIG. 30 is a schematic sectional view taken along the line X₁₂-X₁₂′ inFIG. 29;

FIG. 31 is a schematic plan view of a fourth resist pattern formed onthe third nonmagnetic nonconductive layer in the process of head sliderproduction;

FIG. 32 is a schematic sectional view taken along the line X₁₃-X₁₃′ inFIG. 31;

FIG. 33 is a schematic plan view of an upper nonmagnetic conductivelayer and upper shielding layer formed on the third nonmagneticconductive layer in the process of head slider production;

FIG. 34 is a schematic sectional view taken along the line X₁₄-X₁₄′ inFIG. 33;

FIG. 35 is a schematic plan view of a fourth nonmagnetic nonconductivelayer formed on the substrate and polished until the surface of theupper shielding layer is exposed, in the process of head sliderproduction;

FIG. 36 is a schematic sectional view taken along the line X₁₅-X₁₅′ inFIG. 35;

FIG. 37 is a schematic plan view of a fifth nonmagnetic nonconductivelayer formed on the flattened substrate in the process of head sliderproduction;

FIG. 38 is a schematic sectional view taken along the line X₁₆-X₁₆′ inFIG. 37;

FIG. 39 is a schematic plan view of an upper core layer formed on thefifth nonmagnetic nonconductive layer in the process of head sliderproduction;

FIG. 40 is a schematic sectional view taken along the line X₁₇-X₁₇′ inFIG. 39;

FIG. 41 is a schematic plan view of a sixth nonmagnetic nonconductivelayer formed on the substrate and polished until the surface of theupper core layer is exposed, in the process of head slider production;

FIG. 42 is a schematic sectional view taken along the line X₁₈-X₁₈′ inFIG. 41;

FIG. 43 is a schematic plan view of thin-film coils, back yokes and leadwires formed on the flattened substrate in the process of head sliderproduction;

FIG. 44 is a schematic plan view of external connection terminals formedon the ends of the lead wires in the process of head slider production;

FIG. 45 is a schematic sectional view of a protective layer formed onthe substrate and polished until the surface of the external connectionterminal is exposed, in the process of head slider production;

FIG. 46 is a schematic plan view of a plurality of bar-like head blocksformed by cutting the substrate into stripe shapes in the process ofhead slider production; and

FIG. 47 is a schematic perspective view of a plurality of head slidersproduced by splitting the head block into individual head chips in theprocess of head slider production.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Note that the drawings referred to in the following description wereprepared with characteristic portions of the magnetic head beingenlarged in scale for easier understanding and thus not all thedimensional ratios between the component elements of the magnetic headare the same as those in the actual magnetic head according to thepresent invention.

Referring now to FIG. 4, there is schematically illustrated in the formof a schematic perspective view a hard disc drive as an embodiment ofthe present invention. The hard disc drive body is generally indicatedwith a reference 1. Normally, the hard disc drive body 1 is encased inan enclosure (not shown). As shown, the hard disc drive body 1 has achassis 2 on which there are provided magnetic discs 3 rotated by aspindle motor (not shown), and a head actuator 5 provided at an endthereof with a head slider 4 having mounted thereon a magnetic headwhich writes or reads an information signal to or from the magnetic disc3.

The hard disc drive is further provided, on a side of the chassis 2opposite to the side on which the magnetic disc 3, head actuator 5 etc.are installed, with a signal processing circuit to process theinformation signal at the time of information write or read, controlcircuits 6 including a servo control circuit for servo control of themagnetic head, system controller to control the entire system and othercontrol circuits.

The magnetic disc 3 is a so-called hard disc, and includes a generallydisc-shaped substrate having a central hole formed therein, and amagnetic layer, protective layer, etc. formed one on the other on thesubstrate. In this hard disc drive, a plurality of magnetic discs 3 isfitted at the central hole thereof on a rotary shaft 7 of the spindlemotor and fixed by a damper 8. As the spindle motor controlled by thecontrol circuit is rotated, the magnetic disc 3 is rotated at apredetermined velocity in the direction of arrow A in FIG. 4.

The head actuator 5 includes a support arm 10 pivotable about a spindle9 thereof, a voice coil motor 11 provided at one end of the support arm10, a suspension 12 fixed at the other end of the support arm 10 andhaving a predetermined elasticity, and the head slider 4 installed tothe free end of the suspension 12.

The voice coil motor 11 has a coil 13 installed to the support arm 10and a magnet 14 installed to the chassis 2 oppositely to the coil 13.When supplied with a current, the coil 13 generates a magnetic field,and the magnetic action with the magnet 14 disposed opposite to the coil13 will have the support arm 10 rotate through a predetermined angleabout the spindle 9 in the direction of arrow B in FIG. 4, that is,radially of the magnetic disc 3.

Further, the suspension 12 has the head slider 4 mounted on the free endthereof. It elastically forces the head slider 4 towards the magneticdisc 3 while supporting the had slider 4.

As will be seen from FIGS. 4 and 5, the head slider 4 is molded to begenerally rectangular and so supported on the free end of eachsuspension 12 of each support arm 10 provided for each magnetic disc 3as to be opposite to the signal recording layer of the magnetic disc 3.Also, the head slider 4 has a surface 4 a opposite to the magnetic disc3 (the surface will be referred to as “medium-opposite face” hereunder),on which there is formed an airborne surface (ABS) to produce alevitation force by an air flow produced when the magnetic disc 3 isrotated.

More specifically, while the head slider 4 installed at the free end ofthe suspension 12 is being levitated a predetermined distance off andover the magnetic disc 3 by an air flow produced by the magnetic disc 3being rotated, the magnetic head 20 mounted on the head slider 4 writesor reads a signal to or from the signal recording layer of the magneticdisc 3. Note that the shape of the ABS surface of the head slider 4 isnot limited to any special one but may be an arbitrary one.

The magnetic head is generally indicated with a reference 20. As shownin FIG. 4, the magnetic head 20 is positioned at the rear end of thehead slider 4 traveling in levitation oppositely to the magnetic disc 3rotated in the direction of arrow A in FIG. 4.

As shown in FIGS. 5 and 6, the magnetic head 20 is a composite typethin-film magnetic head including a combination of a magnetic tunneleffect type magnetic head (will be referred to as “TMR head” hereunder)21 as a read head and an inductive type thin-film head 22 as a writehead, for example. Note that FIG. 6 is a schematic end view of themagnetic head 20 from the medium-opposite face 4 a.

In the magnetic head 20, component elements such as the read and writeheads are formed by a thin-film forming technology such as plating,sputtering or the like. Therefore, advantageously, the track and gap caneasily be reduced in size and write/read be done with a high resolution.

More particularly, the magnetic head 20 is produced by adopting athin-film laminating process which will further be described later. Inthe magnetic head 20, the TMR head 21 as a read head to read a signalfrom the magnetic disc 3 under the magnetic tunnel effect is formed on asubstrate 23 of a hard nonmagnetic material such as alumina titaniumcarbide (AL₂O₃—TiC), and the inductive type thin-film head 22 as a writehead to write a signal to the magnetic disc 3 by the action ofelectromagnetic induction. In the magnetic head 20, the componentelements forming each of the read and write heads are exposed from themedium-opposite face 4 a and generally flush with each other.

The TMR head 21 and inductive type thin-film head 22 will further bedescribed below. First, the above TMR head 21 is a so-called shieldedTMR head including a magnetic tunnel junction element (will be referredto as “TMR element” hereunder) sandwiched with shielding gap layersbetween a pair of upper and lower magnetic shielding layers. Morespecifically, the TMR head 21 includes, as shown in FIG. 6, a lowershielding layer 24 formed on the substrate 23, a lower nonmagneticconductive layer 25 formed on the lower shielding layer 24, a TMRelement 26 formed on the lower nonmagnetic conductive layer 25, an uppernonmagnetic conductive layer 27 formed on the TMR element 26, and anupper shielding layer 28 formed on the upper nonmagnetic conductivelayer 27. A nonmagnetic nonconductive material 29 such as Al₂O₃ isfilled in the space around the layers including from the substrate 23 tothe upper shielding layer 28.

The TMR element 26 is a magnetic sensor which detects a signal from themagnetic disc 3 under the so-called magnetic tunnel effect. The magnetictunnel effect is such that the conductance of a tunnel current flowingthrough the TMR element 26 varies depending upon the direction ofmagnetization by a magnetic field from the magnetic disc 3. The magnetictunnel effect is used to detect a voltage change of the tunnel currentand read a signal recorded in th magnetic disc 3.

More specifically, the TMR element 26 includes a magnetic tunneljunction layer 33 formed by laminating a fixed-magnetization layer 30magnetizable only in a predetermined fixed direction and afree-magnetization layer 31 magnetizable in a direction which variesdepending upon an external magnetic field, with a tunnel barrier layer32 laid between these layers 30 and 31.

In the magnetic tunnel junction layer 33, the fixed-magnetization layer30 has a three-layer structure in which, for example, an NiFe layer of 3nm in thickness, IrMn layer of 10 nm in thickness and a CoFe layer of 4nm in thickness are laminated one on the other on a Ta layer of 3 nm inthickness formed as a lower layer on the lower nonmagnetic conductivelayer 25. The above IrMn layer is an antiferromagnetic layer which is inexchange coupling with the CoFe layer which is thus magnetized in apredetermined direction.

Also, the tunnel barrier layer 32 is for example an aluminum oxide(Al₂O₃) layer of 1.3 nm in thickness as an insulative layer formed onthe CoFe layer of the fixed-magnetization layer 30.

The free-magnetization layer 31 is of a two-layer structure in which forexample, a CoFe layer of 4 nm in thickness is formed on the tunnelbarrier layer 32 and an NiFe layer of 5 nm in thickness is formed on theCoFe layer. Further on the free-magnetization layer 31, there is formedfor example a Ta layer of 5 nm in thickness as an upper layer. The aboveCoFe layer is intended to increase the spin polarizability. The NiFelayer has a small coercive force and thus is magnetizable in a directiondepending upon the external magnetic field. These CoFe and NiFe layersform together a magnetic sensor 26 a of the TMR element 26.

When the magnetic tunnel junction layer 33 is made of such a spin valvelaminated structure, the TMR element 26 can have a largemagneto-resistive coefficient or ratio. Note that the materials andthickness of the layers forming the magnetic tunnel junction layer 33are not limited to those having been described in the above but thelayers may be formed from materials appropriately selected and inappropriate thickness, respectively, according to the purpose of use ofthe TMR element 26.

The TMR element 26 is etched in a range from the free-magnetizationlayer 31 to the middle of the fixed-magnetization layer 30 while leavingnot etched the portion of the magnetic tunnel junction layer 33 which isto be the magnetic sensor 26 a of the TMR element 26, so that the trackwidth Tw₁ relative to the magnetic disc 3 is limited. Note that in thisembodiment, the track width Tw₁ is about 5 μm but it may be set to anappropriate value according to the system requirement etc.

In the TMR head 21, the lower shielding layer 24 and lower nonmagneticconductive layer 25 function as electrodes of the fixed-magnetizationlayer 30 of the TMR element 26 while the upper shielding layer 28 andupper nonmagnetic conductive layer 27 function as electrodes of thefee-magnetization layer 31, so that a tunnel current will flow throughthe tunnel barrier layer 32 to the TMR element 26.

More particularly, in the lower nonmagnetic conductive layer 25, thefixed-magnetization layer 30 of the TMR element 26 is electricallyconnected to the lower shielding layer 24. On the other hand, the uppernonmagnetic conductive layer 27 has a projection 27 a which abuts aportion of the TMR element 26 which is to be the magnetic sensor 26 a,and thus the free-magnetization layer 31 of the TMR element 26 and theupper shielding layer 28 are electrically connected to each other viathe projection 27 a.

The lower nonmagnetic conductive layer 25 and upper nonmagneticconductive layer 27 form, together with a nonmagnetic nonconductivematerial 29 disposed in a clearance between the TMR element 26 and thelower and upper shielding layers 24 and 28, a shielding gap layer whichmagnetically isolates the TMR element 26 and the lower and uppershielding layers 24 and 28 from each other.

The lower and upper shielding layers 24 and 28 are formed each from anamorphous lamination layer of CoZrNbTa of 2.3 μm in thickness forexample. The lower and upper shielding layers 24 and 28 will supply anelectricity to the TMR element 26 through the lower and uppernonmagnetic conductive layers 25 and 27.

The lower and upper shielding layers 24 and 28 are wide enough tomagnetically shield the TMR element 26 and thus provide a pair ofmagnetic shielding layers which sandwiches the TMR element 26 betweenthe lower and upper nonmagnetic conductive layers 25 and 27 laid betweenthem, thereby preventing a portion, not to be read, of a signal magneticfield from the magnetic disc 3 from being led to the TMR element 26.That is, in the TMR head 21, a signal magnetic field not to be read bythe TMR element 26 is led to the lower and upper shielding layers 24 and28 while only a signal magnetic field to be read is led to the TMRelement 26. Thus, in the TMR head 21, the TMR element 26 has an improvedfrequency characteristic and reading resolution.

In the TMR head 21, the distance between the lower and upper shieldinglayers 24 and 28 and the TMR element 26 is a so-called inter-shielddistance (gap length).

In the TMR head 21, there are provided lead wires 34 a and 34 belectrically connected to the lower and upper shielding layers 24 and28, respectively, as shown in FIG. 5. External connection terminals 35 aand 35 b are provided at ends of the lead wires 34 a and 34 b so as tobe exposed from the read end face of the head slider 4.

The lead wires 34 a and 34 b are formed thin from a conductive materialsuch as copper (Cu). Also, the external connection terminals 35 a and 35b are formed from a conductive material such as gold (Au), and can beput into contact with an external circuit when conductors also formedfrom gold (Au) are electrically connected to wiring terminals providedon the suspension 12 by wire bonding or the like method.

On the other hand, the inductive type thin-film head 22 includes, asshown in FIGS. 5 and 6, a lower core layer 36 formed from the samematerial as that of the upper shielding layer 28, an upper core layer 38formed on the lower core layer 36 with a magnetic gap 37 laid betweenthem, a back yoke 39 joined to the upper core layer 38 and formingtogether with the lower core layer 36 a back gap at the other end spacedfrom the medium-opposite face 4 a. The clearance between the lower andupper core layers 36 and 38 is filled also with the nonmagneticnonconductive material 29 such as Al₂O₃ for example.

In the inductive type thin-film head 22, there are provided between thelower core layer 36 and back yoke 39 a thin-film coil 40 wound about theback gap and lead wires 41 a and 41 b electrically connected between theinner circumferential end and outer circumferential end of the thin-filmcoil 40. External connection terminals 42 a and 42 b are provided atends of the lead wires 41 a and 41 b so as to be exposed from the readend of the head slider 4.

The lower and upper core layers 36 and 38 and back yoke 39 form togethera magnetic core being a closed magnetic circuit. The core layer 38 ismolded from a conductive soft magnetic material such as amorphouslamination layer to have a predetermined width. The core layer 38 isdisposed opposite to the lower core layer 36 with the nonmagneticnonconductive material 29 laid between them to form the magnetic gap 37whose width is a track width Tw₂. Note that the track width Tw₂ may beset to an appropriate value according to the system requirement etc.

Note that in the inductive type thin-film head 22, a fringing fieldtaking place at the magnetic gap 37 can be thinned by forming aconcavity in the lower core layer 36 oppositely to the upper core layer38 whose width corresponds to the track width Tw₂, whereby even a weakmagnetic signal can be recorded to the magnetic disc 3 with a highaccuracy.

The thin-film coil 40 is spirally formed from a conductive materialssuch as Cu.

The lead wires 41 a and 41 b are formed thin from a conductive materialsuch as Cu similarly to the aforementioned lead wires 34.

Also, the external connection terminals 42 a and 42 b are formed from aconductive material such as gold (Au) similarly to the aforementionedexternal connection terminals 35 (35 a and 35 b), and can be put intocontact with an external circuit when conductors also formed from gold(Au) are electrically connected to wiring terminals provided on thesuspension 12 by wire bonding or the like method.

In the magnetic head 20, the head slider 4 has formed on the rear endface thereof except for a portion thereof where the external connectionterminals 35 and 42 are exposed a protective layer of the nonmagneticnonconductive material 29 such as Al₂O₃ to protect the thin-film coil 40and lead wires 34 and 41.

When a signal is read from the magnetic disc 3 by the TMR head 21 of themagnetic head 20 constructed as having been described in the foregoing,a predetermined voltage is applied between the fixed-magnetization layer30 and free-magnetization layer 31 of the TMR element 26. At this time,the conductance of a tunnel current flowing through the tunnel barrierlayer 32 of the TMR element 26 varies correspondingly to a signalmagnetic field from the magnetic disc 3. Thus, in the TMR head 21, thevoltage value of the tunnel current through the TMR element 26 willvary. By detecting a variation of the voltage value of the TMR element26, the signal can be read from the magnetic disc 3.

On the other hand, when a signal is written to the magnetic disc 3 bythe inductive type thin-film head 22, the thin-film coil 40 is suppliedwith a current corresponding to a signal to be written. At this time, inthe inductive type thin-film head 22, a magnetic field from thethin-film coil 40 will give a magnetic flux to the magnetic core andcause a fringing field to take place from the magnetic gap 37. Thus,with the inductive type thin-film head 22, the signal can be written tothe magnetic disc 3 by applying the fringing field to the magnetic disc3.

In the magnetic head 20, the TMR head 21 being a read head is themagnetic tunnel effect type magnetic head according to the presentinvention. The lower and upper nonmagnetic conductive layers 25 and 27of the TMR head 21 are formed each from at least one nonmagnetic metallayer containing a metal element selected from Ta, Ti, Cr, W, Mo, V, Nband Zr.

Namely, each of the lower and upper nonmagnetic conductive layers 25 and27 is formed from a single layer containing a metal element selectedfrom Ta, Ti, Cr, W, Mo, V, Nb and Zr or a lamination of at least twolayers containing a metal element selected from Ta, Ti, Cr, W, Mo, V, Nband Zr.

Conventionally, aluminum (Al) is used to form the nonmagnetic metallayer. However, the material such as Ta, Ti, Cr, W, Mo, V, Nb or Zr usedto form the nonmagnetic metal layer in the present invention isrelatively hard and superior in mechanical characteristic to thealuminum.

According to the present invention, the TMR head 21 has the nonmagneticlayer formed from the nonmagnetic conductive material superior inmechanical characteristic to aluminum (Al). When the surface of thenonmagnetic metal layer which is to be the medium-opposite face 4 a ispolished in the process of producing the TMR head, which will further bedescribed later, it can be prevented that the nonmagnetic metal layerswhich are to provide the lower and upper nonmagnetic conductive layers25 and 27 will be elongated without being polished and thus a defectwill be caused in the medium-opposite face 4 a of the TMR head 21 by theelongation of the nonmagnetic metal layers.

In the TMR head 21, the lower and upper nonmagnetic conductive layers 25and 27 may be formed each from at least two nonmagnetic metal layersincluding a metal layer containing a metal element selected from Ta, Ti,Cr, W, Mo, V, Nb and Zr and a metal layer containing a metal elementselected from Al, Pt, Cu and Au.

That is, each of the lower and upper nonmagnetic conductive layers 25and 27 may be formed from a lamination in at least two layers of a metallayer containing a metal element selected from Ta, Ti, Cr, W, Mo, V, Nband Zr and a metal layer containing a metal element selected from Al,Pt, Cu and Au.

Also in this TMR head 21, when the surface of the nonmagnetic metallayer which is to be the medium-opposite face 4 a is polished in theprocess of producing the TMR head, which will further be describedlater, it can be prevented that the nonmagnetic metal layers which areto provide the lower and upper nonmagnetic conductive layers 25 and 27will be elongated without being polished and thus a defect will becaused in the medium-opposite face 4 a of the TMR head 21 by theelongation of the nonmagnetic metal layers.

In this case, of the lamination of two or more nonmagnetic metal layers,the metal layer containing a metal element selected from Al, Pt, Cu andAu can have a surface formed to have a good surface roughness andexcellent smoothness. Since the very smooth metal layer is used to formthe nonmagnetic metal layer which is to provide the lower nonmagneticconductive layer 25, it can be prevented that in the TMR element 26formed on the lower nonmagnetic conductive layer 25, the tunnel barrierlayer 32 formed extremely thin will be ruptured between the fixed- andfree-magnetization layers 30 and 31 which will thus be put into contactwith each other, resulting in an electric short-circuit between them.

Therefore, in the TMR head 21, it is possible to prevent themagneto-resistive coefficient of the TMR element 26 from being lower andthus assure a stable playback output.

Also in the TMR head 21, the lower and upper nonmagnetic conductivelayers 25 and 27 may be formed from at least one nonmagnetic metal layercontaining an alloy of two or more elements selected from Al, Pt, Cu,Au, Ta, Ti, Cr, W, Mo, V, Nb and Zr.

That is, the lower and upper nonmagnetic conductive layers 25 and 27 maybe formed from a single layer containing an alloy of two or moreelements selected from Al, Pt, Cu, Au, Ta, Ti, Cr, W, Mo, V, Nb and Zror a lamination of at least two layers containing an alloy of two ormore elements selected from Al, Pt, Cu, Au, Ta, Ti, Cr, W, Mo, V, Nb andZr

Also in this TMR head 21, when the surface of the nonmagnetic metallayer which is to be the medium-opposite face 4 a is polished in theprocess of producing the TMR head, which will further be describedlater, it can be avoided that the nonmagnetic metal layers which are toprovide the lower and upper nonmagnetic conductive layers 25 and 27 willbe elongated without being polished and thus a defect will be caused inthe medium-opposite face 4 a of the TMR head 21 by the elongation of thenonmagnetic metal layers.

Also it can be avoided that in the TMR element 26, the tunnel barrierlayer 32 being extremely thin is ruptured between the fixed- andfree-magnetization layers 30 and 31 which will thus be put into contactwith each other, resulting in an electric short-circuit between them.

As having been described in the foregoing, since the TMR head 21 canhave the good opposite face 4 a opposite to the magnetic disc 3 and thegap between the TMR element 26 and lower and upper shielding layers 24and 28 can be narrow, it is possible to record data to a magneticrecording medium with a high density.

Also, in this hard disc drive, since the TMR head 21 can have a goodface 4 a opposite to the magnetic disc 3, it can provide a stableplayback output and properly read data from the magnetic disc 3.

Next, the method of producing the head slider 4 on which theaforementioned magnetic head 20 is mounted will be described.

Note that in the drawings referred to in the following description,characteristic portions of the magnetic head are enlarged in scale as inFIGS. 4 to 6 for easier understanding and thus not all the dimensionalratios between the component elements are the same as those in theactual magnetic head according to the present invention. Also, in thefollowing description, component elements of the magnetic head 20,materials, sizes and layer thickness of the component elements will bedescribed in detail; however, the present invention are not limited tothe embodiments which will be described herebelow. For example, aso-called shielded TMR head having a similar structure to that actuallyused in the hard disc drives will be described by way of example in thefollowing but it may be a magnetic head of a so-called yoke type using asoft magnetic material as a part of the magnetic circuit. Namely, thepresent invention is not always limited to such an example.

Referring now to FIGS. 7 and 8, there is illustrated a plan view of afirst soft magnetic layer formed on a substrate in the process of headslider production. FIG. 7 is a schematic plan view of the first softmagnetic layer, and FIG. 8 is a schematic sectional view taken along theline X₁-X₁′ in FIG. 7. First in the production of the magnetic head 20,there is prepared a disc-like substrate 50 of about 4 inches in diameterfor example, as shown in FIGS. 7 and 8. The surface of the substrate 50is mirror-finished. Then, a first soft magnetic layer 51 which is toprovide the upper shielding layer 24 is formed on the substrate 50 bysputtering or the like method.

The substrate 50 is to finally be the substrate 23 of the aforementionedmagnetic had 20. After various component elements of the magnetic head20 are formed one after another on the main side of the substrate 50 bythe thin-film forming process, the substrate 50 is cut into individualhead chips, whereby a plurality of head sliders 4 each having themagnetic head 20 mounted thereon can be produced collectively.

Note that the substrate 50 should preferably be formed from aluminatitanum carbide (Al₂O₃—TiC) or the like. On the other hand, the firstsoft magnetic layer 51 is formed from an amorphous lamination layer ofCoZrNbTa of 2.3 μm in thickness for example.

Next, referring to FIGS. 9 and 10, there is illustrated a first resistpattern formed on the first soft magnetic layer 51 in the process ofhead slider production. FIG. 9 is a schematic plan view of the firstresist pattern and FIG. 10 is a schematic sectional view taken along theline X₂-X₂′ in FIG. 9. A photoresist is applied to the first softmagnetic layer 51 and cured to form a resist layer. The photolithographyis utilized to pattern the resist layer to a predetermined form, therebyforming a first resist pattern 52 as shown in FIGS. 9 and 10. Morespecifically, for patterning the resist layer to have the predeterminedpattern, first the resist layer is exposed correspondingly to a desiredpattern. Next, the exposed portions of the resist layer are solved andremoved in a developing solution, and then subjected to post-baking.Thus, a resist pattern of the predetermined form is provided.

Next, referring to FIGS. 11 and 12, there is illustrated the lowershielding layer 24 formed on the substrate 50 in the process of headslider production. FIG. 11 is a schematic plan view of the lowershielding layer 24 formed on the substrate 50 and FIG. 12 is a schematicsectional view taken along the line X₃-X₃′ in FIG. 11. Using the firstresist pattern 52 as a mask, the first soft magnetic layer 51 is etchedby dry etching, and then the first resist pattern is removed from on thefirst soft magnetic layer 51. Thus, a plurality of lower shieldinglayers 24 is formed as shown in FIGS. 11 and. 12. Note that the lowershielding layer 24 should be formed sufficiently large to magneticallyshield the lower layer of the TMR element 26 which is to be formed inthe later process.

Next, referring now to FIGS. 13 and 14, there is illustrated a firstnonmagnetic nonconductive layer 54 formed on the substrate 50 andpolished until the surface of the lower shielding layer 24 is exposed,in the process of head slider production. FIG. 13 is a schematic planview of the first nonmagnetic nonconductive layer 54 formed on thesubstrate 50 and FIG. 14 is a schematic sectional view taken along theline X₄-X₄′ in FIG. 13. As shown, a first nonmagnetic nonconductivelayer 53 is formed from Al₂O₃ for example by sputtering over thesubstrate 50, and then the layer 53 is polished until the plurality oflower shielding layers 24 formed on the substrate 50 is exposed. Thus,the first nonmagnetic nonconductive layer 53 is embedded between thesubstrate 50 and lower shielding layers 24 to provide a flat surfacewhere the lower shielding layers are formed on the substrate 50.

Next, referring to FIGS. 15 and 16, there is illustrated the firstnonmagnetic conductive layer 54 formed on the flattened substrate 50 inthe process of head slider production. FIG. 15 is a schematic plan viewof the first nonmagnetic conductive layer 54 formed on the flattenedsubstrate 50 and FIG. 16 is a schematic sectional view taken along theline X₅-X₅′ in FIG. 15. At this step of the head slider productionprocess, sputtering or the like method is utilized to form on thesubstrate 50 the first nonmagnetic conductive layer 54 which is toprovide the lower nonmagnetic conductive layer 25 as shown. The firstnonmagnetic conductive layer 54 is the previously mentioned nonmagneticmetal layer whose thickness may be set to an appropriate valuecorrespondingly to the frequency etc. of a signal recorded in a magneticrecording medium. The thickness is about 100 nm for example.

Next, referring now to FIGS. 17 and 18, there is illustrated a magnetictunnel junction layer 55 formed on the first nonmagnetic conductivelayer 54 in the process of head slider production. FIG. 17 is aschematic plan view of the magnetic tunnel junction layer 55 formed onthe first nonmagnetic conductive layer 54 and FIG. 18 is a schematicsectional view taken along the line X₆-X₆′ in FIG. 17. As shown, themagnetic tunnel junction layer 55 which is to provide the aforementionedmagnetic tunnel junction layer 33 is formed by sputtering or the like onthe first nonmagnetic conductive layer 54.

As will be seen, the magnetic tunnel junction layer 55 is formed, bysputtering or the like, from a lamination of a Ta layer of 3 nm inthickness as a lower layer, a NiFe layer of 3 nm as thefixed-magnetization layer 30, an IrMn layer of 10 nm and CoFe layer of 4nm, an aluminum oxide (Al₂O₃) layer of 1.3 nm as the tunnel barrierlayer 32, a CoFe layer of 4 nm and NiFe layer of 5 nm as thefree-magnetization layer 31, and a Ta layer of about 5 nm in thicknessas an upper layer, laminated one on the other in this order.

Note that the materials and thickness of the layers composing togetherthe above magnetic tunnel junction layer 55 are not limited to the aboveones but may be properly selected correspondingly to the purpose of useof the TMR element 26.

Next, referring to FIGS. 19 and 20, there is illustrated a second resistpattern 56 formed on the magnetic tunnel junction layer 55 in theprocess of head slider production. FIG. 19 is a schematic plan view ofthe second resist pattern formed on the magnetic tunnel junction layer55 and FIG. 20 is a schematic sectional view taken along the line X₇-X₇′in FIG. 19. A photoresist is applied to the magnetic tunnel junctionlayer 55 and cured to form a resist layer. Then, the photolithography isutilized to pattern the resist layer to a predetermined form, therebyforming the second resist pattern 56 as shown.

Next, referring to FIGS. 21 and 22, there is illustrated the lowernonmagnetic conductive layer 25 and magnetic tunnel junction layer 55formed on the lower shielding layer 24 in the process of head sliderproduction. FIG. 21 is a schematic plan view of the lower nonmagneticconductive layer 25 and magnetic tunnel junction layer 55 formed on thelower shielding layer 24 and FIG. 22 is a schematic sectional view takenalong the line X₈-X₈′ in FIG. 21. As shown, the second resist pattern 56is used as a mask to etch the magnetic tunnel junction layer 55 andfirst nonmagnetic conductive layer 54 and then the second resist pattern56 is removed. Thus, there is formed on the lower shielding layer 24 thelower nonmagnetic conductive layer 25 and magnetic tunnel junction layer33, having the predetermined form.

Next, referring to FIGS. 23 and 24, there is illustrated a secondnonmagnetic nonconductive layer 57 and magnetic tunnel junction layers33 formed on the substrate 50 and polished until the surface of themagnetic tunnel junction layer 33 is exposed, in the process of headslider production. FIG. 23 is a schematic plan view of the secondnonmagnetic nonconductive layer 57 and magnetic tunnel junction layers33 formed on the substrate 50 and polished until the surface of themagnetic tunnel junction layer 33 is exposed, and FIG. 24 is a schematicsectional view taken along the line X₉-X₉′ in FIG. 23. As shown,sputtering or the like is used to form the second nonmagneticnonconductive layer 57 of Al₂O₃ for example over the substrate 50, andthen the second magnetic nonconductive layer 57 is polished until theplurality of magnetic tunnel junction layers 33 formed on the substrate50 is exposed. Thus, the second nonmagnetic nonconductive layer 57 isembedded between the substrate 50 and lower nonmagnetic conductive layer25 and magnetic tunnel junction layers 33 to provide a flat surfacewhere the lower nonmagnetic conductive layer 25 and magnetic tunneljunction layers 33 are not formed on the substrate 50.

Next, referring to FIGS. 25 and 26, there is illustrated a recess formedaround a portion of the magnetic tunnel junction layer 33 which is to bethe magnetic sensor 26 a of the TMR element 26 in the process of headslider production. FIG. 25 is a schematic plan view, enlarged in scale,a portion C shown in FIG. 23, and FIG. 26 is a schematic sectional viewtaken along the line X₁₀-X₁₀′ in FIG. 25. As shown, a photoresist isapplied to the flattened substrate 50 and cured to form a resist layer.The photolithography is utilized to pattern the resist layer to apredetermined form. Then, the patterned resist layer is used as a maskto etch, by ion etching, the magnetic tunnel junction layer 33 in arange from the free-magnetization layer 31 to the middle of thefixed-magnetization layer 30 except for a portion of the layer 33 whichis to be the magnetic sensor 26 a of the TMR element 26. Thereafter, theresist layer is removed from on the substrate 50. Thus, the track widthTw₁ of the TMR element 26 relative to the magnetic disc 3 is defined.Note that the track width Tw₁ is about 5 μm in this embodiment but it isnot limited to this value. The track width Tw₁ may be set to anappropriate value according to the system requirement.

Next, referring to FIGS. 27 and 28, there is illustrated a third resistpattern 58 formed right above the magnetic sensor 26 a of the TMRelement 26 in the process of head slider production. FIG. 27 is aschematic plan view, enlarged in scale, of the portion C in FIG. 23 andFIG. 28 is a schematic sectional view taken along the line X₁₁-X₁₁′ inFIG. 27. A photoresist is applied to the substrate 50 and cured to forma resist layer. The photolithography is utilized to pattern the resistlayer to a predetermined form, thereby forming the third resist pattern58 right above the magnetic sensor 26 a of the TMR element 26 as shownin FIGS. 27 and 28.

Next, referring to FIGS. 29 and 30, there is illustrated a thirdnonmagnetic nonconductive layer having a contact hole, formed rightabove the magnetic sensor 26 a of the TMR element 26 in the process ofhead slider production. FIG. 29 is a schematic plan view, enlarged inscale, of the portion C shown in FIG. 23 and FIG. 30 is a schematicsectional view taken along the line X₁₂-X₁₂′ in FIG. 29. The thirdresist pattern 58 is used to form, by sputtering or the like, a thirdnonmagnetic nonconductive layer 59 of Al₂O₃ for example, and then thethird resist pattern 58 is removed along with the third nonmagneticnonconductive layer 59 on the third resist layer 58, whereby there isformed the third nonmagnetic nonconductive layer 59 having a contacthole 60 open right above the magnetic sensor 26 a of the TMR element 26.

Next, referring to FIGS. 31 and 32, there is illustrated a fourth resistpattern formed on the third nonmagnetic nonconductive layer 59 in theprocess of head slider production. FIG. 31 is a schematic plan view,enlarged in scale of the portion C shown in FIG. 23, and FIG. 32 is aschematic sectional view taken along the line X₁₃-X₁₃′ in FIG. 31. Asshown, a photoresist is applied to the third nonmagnetic nonconductivelayer 59 and cured to form a resist layer. The photolithography isutilized to pattern the resist layer to a predetermined form, therebyforming a fourth resist pattern 61 having an opening 61 a having apredetermined form as shown in FIGS. 31 and 32.

Next, referring to FIGS. 33 and 34, there is illustrated an uppernonmagnetic conductive layer and upper shielding layer 28 formed on thethird nonmagnetic conductive layer 59 in the process of head sliderproduction. FIG. 33 is a schematic plan view, enlarged in scale, of theportion C shown in FIG. 23, and FIG. 34 is a schematic sectional viewtaken along the line X₁₄-X₁₄′ in FIG. 33. As shown, the fourth resistpattern 61 is used to form, by sputtering or the like, a secondnonmagnetic conductive layer 62 which is to provide the uppernonmagnetic conductive layer 27. At this time, the second nonmagneticconductive layer 62 will be embedded in the contact hole 60 in the thirdnonmagnetic nonconductive layer 59. Thus, the projection 27 a of theupper nonmagnetic conductive layer 27, which is to abut the magneticsensor 26 a of the TMR element 26, is formed. Note that the secondnonmagnetic conductive layer 62 is formed from the aforementionedmagnetic metal layer whose thickness may be set to an appropriate valuecorrespondingly to the frequency etc. of a signal recorded in a magneticrecording medium.

Then, sputtering or the like is used to form, on the second nonmagneticconductive layer 62, a second soft magnetic layer 63 which is to providethe upper shielding layer 28 and lower core layer 36. The second softmagnetic layer 63 is formed from an amorphous lamination layer ofCoZrNbTa of 2.3 μm for example. Note that the second soft magnetic layer63 may be formed from other than the amorphous lamination layer and itmay be formed by the use of any other method than the sputtering such asplating or evaporation for example.

Then, the fourth resist pattern 61 is removed along with the secondnonmagnetic conductive layer 62 and second soft magnetic layer 63 formedon the fourth resist pattern 61. Thus, there are formed on the thirdnonmagnetic nonconductive layer 59 the upper nonmagnetic conductivelayer 27 and upper shielding layer 28.

Next, referring to FIGS. 35 and 36, there is illustrated a fourthnonmagnetic nonconductive layer 64 formed on the substrate 50 andpolished until the surface of the upper shielding layer 28 is exposed,in the process of head slider production. FIG. 35 is a schematic planview, enlarged in scale, of the portion C shown in FIG. 23, and FIG. 36is a schematic sectional view taken along the line X₁₅-X₁₅′ in FIG. 35.The second nonmagnetic nonconductive layer 64 of Al₂O₃ for example isformed by sputtering or the like over the substrate 50, and thenpolished until the plurality of upper shielding layers 28 formed on thesubstrate 50 is exposed. Thus, the fourth nonmagnetic nonconductivelayer 64 is embedded between the substrate 50 and upper shielding layers28 to provide a flat surface where the upper shielding layers 28 are notformed on the substrate 50.

Next, referring to FIGS. 37 and 38, there is illustrated a fifthnonmagnetic nonconductive layer 65 formed on the flattened substrate 50in the process of head slider production. FIG. 37 is a schematic planview, enlarged in scale, of the portion C shown in FIG. 23, and FIG. 38is a schematic sectional view taken along the line X₁₆-X₁₆′ in FIG. 37.As shown, the fifth nonmagnetic nonconductive layer 65 which is toprovide the magnetic gap 37 is formed by sputtering or the like on theflattened substrate 50. The fifth nonmagnetic nonconductive layer 65should preferably be formed from A1 ₂O₃ or the like.

Next, referring to FIGS. 39 and 40, there is illustrated the upper corelayer 38 formed on the fifth nonmagnetic nonconductive layer 66 in theprocess of head slider production. FIG. 39 is a schematic plan view,enlarged in scale, of the portion C shown in FIG. 23, and FIG. 40 is aschematic sectional view taken along the line X₁₇-X₁₇′ in FIG. 39. Asshown, a photoresist is applied to the firth nonmagnetic nonconductivelayer 65 and cured to form a resist layer. The photolithography isutilized to pattern the resist layer to a predetermined form. Thepatterned resist layer is used to form a third soft magnetic layer 66 bysputtering or the like from an amorphous lamination layer for example,and then the resist layer is removed along with the third soft magneticlayer 66 formed on the resist layer. Thus, the upper core layer 38having a predetermined width is formed on the fifth nonmagneticnonconductive layer 64. Also, the fifth nonmagnetic nonconductive layer64 is disposed opposite to the lower core layer 38 with the fifthnonmagnetic nonconductive layer 65 being laid between them to define themagnetic gap 37 whose width is a track width Tw₂. Note that the trackwidth Tw₂ may be set to an appropriate value correspondingly to thesystem requirement.

Next, referring to FIGS. 41 and 42, there is illustrated a sixthnonmagnetic nonconductive layer 67 formed on the substrate 50 andpolished until the surface of the upper core layer is exposed, in theprocess of head slider production. FIG. 41 is a schematic plan view,enlarged in scale, of the portion C shown in FIG. 23, and FIG. 42 is aschematic sectional view taken along the line X₁₈-X₁₈′ in FIG. 41. Thesixth nonmagnetic nonconductive layer 67 of Al₂O₃ for example is formedby sputtering or the like over the substrate 50, and then polished untilthe plurality of upper core layers 38 formed on the substrate 50 isexposed. Thus, the sixth nonmagnetic nonconductive layer 67 is embeddedbetween the substrate 50 and upper core layers 38 to provide a flatsurface where no upper core layers 38 are formed on the substrate 50.

Next, the thin-film coils 40, back yokes 39 and lead wires 34 and 41 areformed on the flattened substrate 50 as shown in FIG. 43.

The thin-film coil 40 is spirally formed by sputtering around a portionwhere the lower core layer 36 and back yoke 39 abut each other, and anonmagnetic nonconductive layer is formed to cover the thin-film coil40. The thin-film coil 40 is formed from a conductive material such asCu.

The back yoke 39 is formed in junction with the upper core layer 38while abutting the lower core layer 36 at a generally central portion ofthe spirally formed thin-film col 40. Thus, the lower core layer 36,upper core layer 38 and back yoke 39 will form together the inductivetype thin-film head 22.

As the lead wires 34 and 41, there are formed the lead wires 34 a and 34b which are to electrically be connected to the lower and uppershielding layers 24 and 28, respectively, and the lead wires 41 a and 41b which are to electrically be connected to the inner and outercircumferential ends, respectively, of the thin-film coil 40. Moreparticularly, the photolithography is utilized to pattern a photoresistto a predetermined form. Etching is effected using the photoresist as amask to form the lower and upper shielding layers 24 and 28 and aterminal recess in which a portion abutting the inner and outercircumferential ends of the thin-film coil 40 is exposed. A conductivelayer of Cu having a thickness of about 6 μm is formed by electroplatingusing a copper sulfate solution for example, and then the photoresist isremoved along with the conductive layer formed on the photoresist. Thus,the lower and upper shielding layers 24 and 28, inner and outercircumferential ends of the thin-film coil 40, and the conductive layerembedded in the terminal recess are electrically connected to eachother. Then, a conductive layer of Cu having a predetermined form isformed by electroplating using a copper sulfate solution so as to bejoined to the conductive layer embedded in the terminal recess. Thus,the lead wires 34 a, 34 b, 41 a and 41 b are formed as shown in FIG. 43.Note that the conductive layer may be formed by a method other than theelectroplating so long as it will not adversely affect the other layers.

Next, the external connection terminals 35 and 42 are formed on the endsof the lead wires 34 and 41, respectively, as shown in FIG. 44. As theexternal connection terminals 35 and 42, there are formed the externalconnection terminals 35 a and 35 b which are to electrically beconnected to the lead wires 34 a and 34 b, respectively, and theexternal connection terminals 42 a and 42 b which are to electrically beconnected to the lead wires 41 a and 41 b, respectively. Moreparticularly, the photolithography is utilized to pattern a photoresistto a predetermined form. The patterned photoresist is used to form aconductive layer of Au by sputtering, electroplating or the like forexample, and the photoresist is removed along with the conductive layerformed on the photoresist. Thus, there will be formed the externalconnection terminals 35 a, 35 b, 42 a and 42 b as shown in FIG. 46.

Next, a protective layer 68 of Al₂O₃ for example is formed, as shown inFIG. 45, by sputtering or the like over the substrate 50, and thenpolished until the external connection terminals 35 and 42 formed on thesubstrate 50 are exposed. More specifically, the protective layer 68 isformed from Al₂O₃ for example by sputtering to a thickness of about 4μm. Note that the protective layer 68 can be formed from other thanAl₂O₃ so long as this material is nonmagnetic and nonconductive. Takingthe hostile-environment property and abrasion resistance inconsideration, the protective layer 68 should preferably be formed fromAl₂O₃. Also, to form the protective layer 60, the evaporation processfor example may be adopted instead of the sputtering. The externalconnection terminals 35 and 42 are polished until their surfaces areexposed. In this polishing, for example abrasive grains of diamond ofabout 2 μm in grain size are used to polish the external connectionterminals 35 and 42 until their surfaces are exposed. Then, the surfacesare buffed with silicon abrasive grains for mirror-finish of thesurfaces. Thus, there can be obtained the substrate 50 having formedthereon a plurality of head elements 69 which will eventually be themagnetic head 20.

Next, the substrate 50 having the plurality of head elements 69 formedthereon is cut into strips as shown in FIG. 46 to provide bar-like headblocks 70 in which there are arranged side-by-side the head elements 69which are to form the magnetic heads 20.

Next, the surface of the head block 70 which is to be themedium-opposite face 4 a is polished on a surface plate to adjusts theheight of the head element 69.

Conventionally, in case the first and second nonmagnetic conductivelayers 54 and 62 which are to provide the lower and upper nonmagneticconductive layers 25 and 27, respectively, are formed from Al forexample, when the above polishing is effected, the first and secondnonmagnetic conductive layers 54 and 62 which are to provide the lowerand upper nonmagnetic conductive layers 25 and 27 will be elongatedwithout being polished and thus a defect will be caused in themedium-opposite face 4 a of the TMR head 21 of the head slider 4 by theelongation of the first and second nonmagnetic conductive layers 54 and62.

However, since the first and second nonmagnetic conductive layers 54 and62 which are to provide the lower and upper nonmagnetic conductivelayers 25 and 27, respectively, are formed from the aforementionednonmagnetic metal layer, it can be avoided that the first and secondnonmagnetic conductive layers 54 and 62 which are to provide the lowerand upper nonmagnetic conductive layers 25 and 27, respectively, will beelongated without being polished and thus a defect will be caused in themedium-opposite face 4 a of the TMR head 21 by the elongation of thenonmagnetic metal layer.

Thus, the component elements forming together the magnetic head 20 areexposed from the medium-opposite face 4 a and generally flush with eachother.

Next, the head block 70 is recessed and tapered to form the airbornesurface (ABS) of the head slider 4, and then is divided into individualhead chips. Thus, there is produced a plurality of head sliders 4 oneach of which the magnetic head 20 as shown in FIG. 47 is to beinstalled.

For use of the head slider 4 produced as in the foregoing, the headslider 4 is mounted on the free end of the suspension 12, and wiringterminals provided on the suspension 12 are electrically connected tothe external connection terminals 35 and 42 of the magnetic head 20 withconductor of gold (Au) by wire bonding or the like. Thus, the magnetichead 20 can be put into contact with an external circuit. The headslider 4 will be installed to a hard disc drive as shown in FIG. 4 whilebeing mounted on the suspension 12.

With the head slider 4 produced through the aforementioned processes, itcan be prevented that when the head block 70 is polished, thenonmagnetic metal layers which are to provide the lower and uppernonmagnetic conductive layers 25 and 27 of the TMR head 21 will beelongated without being polished and thus a defect will be caused in themedium-opposite face 4 a of the TMR head 21 by the elongation of thenonmagnetic metal layers.

Concerning each shielded TMR head formed from a single layer of Al, Cu,Au, Pt, Ta, Ti, Cr, W, Mo, V, Nb or Zr, as the nonmagnetic metal layerforming each of the lower nonmagnetic conductive layers 25 and 27, andeach shielded TMR head formed from a lamination of a metal layer of Al,Cu, Au or Pt and a metal layer containing a meal element selected fromTa, Ti, Cr, W, Mo, V, Nb and Zr, the yield of production was evaluatedwhen a defect was caused in the shielded TMR head by the elongation ofthe nonmagnetic metal layer.

The results of yield evaluation are shown in Table 1. Note that in Table1, a circle indicates that the yield is 80% or more, triangle indicatesthat the yield is 30% to 80%, and cross mark indicates that the yield isless than 30%.

TABLE 1 Al Cu Au Pt Ta Ti Cr W Mo V Nb Zr Single layer x x x Δ ∘ ∘ ∘ ∘ ∘∘ ∘ ∘ Lamination ∘ ∘ ∘ ∘ / / / / / / / / layer

As seen from the evaluation results shown in Table 1, the yield ofproduction of the TMR head is low in case the TMR head is formed fromAl, Cu or Au of the single layers of Al, Cu, Au and Pt, respectively,which are conventionally used as the nonmagnetic metal layer, and alsothe yield is not high when the TMR head is formed from a Pt layer.

On the contrary, as will be seen from Table 1, when Ta, Ti, Cr, W, Mo,V, Nb or Zr is used as the nonmagnetic metal layer in the TMR headaccording to the present invention, each of the TMR heads can beproduced with a high yield.

It will also be seen that when a lamination of a metal layer of Al, Cu,Au or Pt and a metal layer containing a metal element selected from Ta,Ti, Cr, W, Mo, V, Nb and Zr is used, the TMR head can be produced with ahigh yield.

Also, concerning each shielded TMR head formed from a single layercontaining each of the alloys AlTa, AlTi, AlCr, AlW, AlMo, AlV, AlNb adAlZr as the nonmagnetic metal layer which is used to form the lower andupper nonmagnetic conductive layers 25 and 27, the yield of productionwas evaluated when a defect was caused in the shielded TMR head by theelongation of the nonmagnetic metal layer.

The results of yield evaluation are shown in Table 2. Note that in Table2, a circle indicates that the yield is 80% or more, triangle indicatesthat the yield is 30% to 80%, and cross mark indicates that the yield isless than 30%. For reference, there are also shown the results of yieldevaluation on the shielded TMR heads each formed from a single layer ofAl, Cu, Au or Pt.

TABLE 1 Al Cu Au Pt AlTa AlTi AlCr AlW AlMo AlV AlNb AlZr Single layer xx x Δ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘

As seen from the evaluation results shown in Table 2, the TMR head canbe produced from each of the alloys AlTa, AlTi, AlCr, AlW, AlMo, AlV,AlNb and AlZr as the nonmagnetic metal layer with an improved yield.

In this case, it is evident that the TMR head can be produced with ahigh yield even from a lamination layer including a metal layercontaining each of these alloys.

As having been described in the foregoing, the present invention makesit possible to prevent the lower and upper shielding layers 24 and 28 inthe TMR head 21 from electrically being short-circuited between them,and allow a mass production of a high-yield, high-quality TMR head 21without increase of the manufacturing costs and with a considerablyimproved productivity.

In the foregoing, the present invention has been described concerningthe composite type thin-film magnetic head including the TMR head 21 asthe read head and the inductive type thin-film head 22 as the writehead. It is of course however that the present invention is applicableto a magnetic head constructed from only the TMR head.

Also in the foregoing, the present invention has been describedconcerning the hard disc drive as one example of the recorder/playeraccording to the present invention. However, the present invention isalso applicable to a magnetic disc drive using a flexible disc as therecording medium, a magnetic tape drive using a magnetic tape as therecording medium, and the like.

1. A magnetic tunnel effect type magnetic head comprising: a magnetictunnel junction element sandwiched with upper and lower conductive gaplayers between upper and lower magnetic shielding layers, wherein atleast one of the conductive gap layers is formed from at least onenonmagnetic metal layer containing a metal element selected from Ta, Ti,Cr, W, Mo, V, Nb and Zr, wherein the magnetic tunnel junction elementincludes a free layer on a fixed layer and a tunnel barrier layerdisposed between the free layer and the fixed layer, and wherein a widthof the free layer is equal to or less than a width of the fixed layer.2. A recorder/player which records and/or plays back a signal to and/orfrom a magnetic recording medium comprising: a magnetic tunnel effecttype magnetic head having a magnetic tunnel junction element sandwichedwith conductive gap layers between a pair of magnetic shielding layers,wherein at least one of the conductive gap layers is formed from atleast one nonmagnetic metal layer containing a metal element selectedfrom Ta, Ti, Cr, W, Mo, V, Nb and Zr, wherein the magnetic tunneljunction element includes a free layer on a fixed layer and a tunnelbarrier layer disposed between the free layer and the fixed layer, andwherein a width of the free layer is equal to or less than a width ofthe fixed layer.